Massive heterotopic ossification associated with late deficits in posterior wall of acetabulum after failed acetabular fracture operation

BACKGROUND Heterotopic ossification is a common postoperative complication of acetabular fracture. However, functionally significant heterotopic ossification with associated late bone defects in the posterior wall of the acetabulum is rare and challenging to treat. When heterotopic ossification is a late complication of failed acetabular fracture operation, it is disabling and may only be treated by THA. THA is highly susceptible to premature failure in young and active patients and may require numerous revisions. CASE PRESENTATION This article describes a 40-year-old man with massive heterotopic ossification associated with late bone defects in the posterior wall of the acetabulum after a failed acetabular fracture operation. The primary fracture type was a 62-A2.3 fracture according to the AO/OTA Classification.Surgical excision and anatomical reconstruction of the acetabular wall using heterotopic ossific bone were performed 10 months after the fracture repair. Postoperatively, indomethacin was administered for prophylaxis against recurrence of heterotopic ossification, and hip range of motion was progressively increased. At 5 years and 6 months follow-up, the patient's pain was relieved and hip function had recovered. Though radiography and CT showed minimal subchondral cysts and mild joint-space narrowing, there was no evidence of graft resorption, progressive posttraumatic osteoarthritis or necrosis of the femoral head. CONCLUSION To the authors' knowledge, this is the first case of such a challenging condition. Although it is an extremely rare case, it provides an attractive option for avoiding THA, as the long-term follow-up shows a satisfactory outcome.